I refused to send either of my kids to Berkeley. [mod edit] I like more balanced campuses where kids are challenged by people who see the world differently. Now it is flat out anti-free speech. On top of that, it is loaded with hyper-competitive kids of overbearing parents which, ironically, have made it way less diverse. So, 60 percent of the students do nothing but study and 40 percent spend their time trying to protect their echo chamber.
The UC system is impressive, in general, but Berkeley is a dumpster fire. It is highly rated, sure, but it is NOT what I think of when I think of college.
As you say, college is a place to meet and learn from people who see things differently (as well as the same). Unfortunately, I fear that, over the years, young folks have been to some degree conditioned to feel comfortable in their relatively homogeneous group and so look for a college that will reinforce whatever that comfort group be - from ultra liberal to ultra conservative.
Interestingly, I was in a fairly homogeneous high school group - I differed from almost all the classmates I was friends with only by religious affiliation and having less well-to-do parents, otherwise all were bright, college bound, a bit superior, serious, non-athlete . . . well, you get the drift, and in general, thought the same way about most things. Then they went to a bunch of private schools that my parents couldn't afford and I went to Rutgers. Lived in a dorm, then joined a frat that had members from the very smart to the never-graduated; from the (relatively) prim and proper to the druggie. What an eye-opening experience college was!
Off my soap-box. But yes, I do think diverse thinking matters.